| Path: | README.rdoc |
| Last Update: | Tue Nov 15 16:10:43 +0100 2011 |
Sinatra is a DSL for quickly creating web applications in Ruby with minimal effort:
# myapp.rb
require 'sinatra'
get '/' do
'Hello world!'
end
Install the gem and run with:
gem install sinatra ruby -rubygems myapp.rb
View at: localhost:4567
In Sinatra, a route is an HTTP method paired with an URL matching pattern. Each route is associated with a block:
get '/' do
.. show something ..
end
post '/' do
.. create something ..
end
put '/' do
.. update something ..
end
delete '/' do
.. annihilate something ..
end
Routes are matched in the order they are defined. The first route that matches the request is invoked.
Route patterns may include named parameters, accessible via the params hash:
get '/hello/:name' do
# matches "GET /hello/foo" and "GET /hello/bar"
# params[:name] is 'foo' or 'bar'
"Hello #{params[:name]}!"
end
You can also access named parameters via block parameters:
get '/hello/:name' do |n|
"Hello #{n}!"
end
Route patterns may also include splat (or wildcard) parameters, accessible via the params[:splat] array.
get '/say/*/to/*' do
# matches /say/hello/to/world
params[:splat] # => ["hello", "world"]
end
get '/download/*.*' do
# matches /download/path/to/file.xml
params[:splat] # => ["path/to/file", "xml"]
end
Route matching with Regular Expressions:
get %r{/hello/([\w]+)} do
"Hello, #{params[:captures].first}!"
end
Or with a block parameter:
get %r{/hello/([\w]+)} do |c|
"Hello, #{c}!"
end
Routes may include a variety of matching conditions, such as the user agent:
get '/foo', :agent => /Songbird (\d\.\d)[\d\/]*?/ do
"You're using Songbird version #{params[:agent][0]}"
end
get '/foo' do
# Matches non-songbird browsers
end
Other available conditions are host_name and provides:
get '/', :host_name => /^admin\./ do
"Admin Area, Access denied!"
end
get '/', :provides => 'html' do
haml :index
end
get '/', :provides => ['rss', 'atom', 'xml'] do
builder :feed
end
You can easily define your own conditions:
set(:probability) { |value| condition { rand <= value } }
get '/win_a_car', :probability => 0.1 do
"You won!"
end
get '/win_a_car' do
"Sorry, you lost."
end
The return value of a route block determines at least the response body passed on to the HTTP client, or at least the next middleware in the Rack stack. Most commonly this is a string, as in the above examples. But other values are also accepted.
You can return any object that would either be a valid Rack response, Rack body object or HTTP status code:
That way we can for instance easily implement a streaming example:
class Stream
def each
100.times { |i| yield "#{i}\n" }
end
end
get('/') { Stream.new }
Static files are served from the ./public directory. You can specify a different location by setting the :public option:
set :public, File.dirname(__FILE__) + '/static'
Note that the public directory name is not included in the URL. A file ./public/css/style.css is made available as example.com/css/style.css.
Templates are assumed to be located directly under the ./views directory. To use a different views directory:
set :views, File.dirname(__FILE__) + '/templates'
One important thing to remember is that you always have to reference templates with symbols, even if they‘re in a subdirectory (in this case use :’subdir/template‘). You must use a symbol because otherwise rendering methods will render any strings passed to them directly.
The haml gem/library is required to render HAML templates:
## You'll need to require haml in your app
require 'haml'
get '/' do
haml :index
end
Renders ./views/index.haml.
Haml's options can be set globally through Sinatra‘s configurations, see Options and Configurations, and overridden on an individual basis.
set :haml, :format => :html5 # default Haml format is :xhtml
get '/' do
haml :index, :format => :html4 # overridden
end
## You'll need to require erb in your app
require 'erb'
get '/' do
erb :index
end
Renders ./views/index.erb.
The erubis gem/library is required to render Erubis templates:
## You'll need to require erubis in your app
require 'erubis'
get '/' do
erubis :index
end
Renders ./views/index.erubis.
It is also possible to replace Erb with Erubis:
require 'erubis'
Tilt.register :erb, Tilt[:erubis]
get '/' do
erb :index
end
Renders ./views/index.erb with Erubis.
The builder gem/library is required to render builder templates:
## You'll need to require builder in your app
require 'builder'
get '/' do
builder :index
end
Renders ./views/index.builder.
The nokogiri gem/library is required to render nokogiri templates:
## You'll need to require nokogiri in your app
require 'nokogiri'
get '/' do
nokogiri :index
end
Renders ./views/index.nokogiri.
The haml or sass gem/library is required to render Sass templates:
## You'll need to require haml or sass in your app
require 'sass'
get '/stylesheet.css' do
sass :stylesheet
end
Renders ./views/stylesheet.sass.
Sass' options can be set globally through Sinatra‘s configurations, see Options and Configurations, and overridden on an individual basis.
set :sass, :style => :compact # default Sass style is :nested
get '/stylesheet.css' do
sass :stylesheet, :style => :expanded # overridden
end
The haml or sass gem/library is required to render Scss templates:
## You'll need to require haml or sass in your app
require 'sass'
get '/stylesheet.css' do
scss :stylesheet
end
Renders ./views/stylesheet.scss.
Scss' options can be set globally through Sinatra‘s configurations, see Options and Configurations, and overridden on an individual basis.
set :scss, :style => :compact # default Scss style is :nested
get '/stylesheet.css' do
scss :stylesheet, :style => :expanded # overridden
end
The less gem/library is required to render Less templates:
## You'll need to require less in your app
require 'less'
get '/stylesheet.css' do
less :stylesheet
end
Renders ./views/stylesheet.less.
The liquid gem/library is required to render Liquid templates:
## You'll need to require liquid in your app
require 'liquid'
get '/' do
liquid :index
end
Renders ./views/index.liquid.
Since you cannot call Ruby methods (except for yield) from a Liquid template, you almost always want to pass locals to it:
liquid :index, :locals => { :key => 'value' }
The rdiscount gem/library is required to render Markdown templates:
## You'll need to require rdiscount in your app
require "rdiscount"
get '/' do
markdown :index
end
Renders ./views/index.markdown (md and mkd are also valid file extensions).
It is not possible to call methods from markdown, nor to pass locals to it. You therefore will usually use it in combination with another rendering engine:
erb :overview, :locals => { :text => markdown(:introduction) }
Note that you may also call the markdown method from within other templates:
%h1 Hello From Haml! %p= markdown(:greetings)
It is also possible to parse Markdown with BlueCloth rather than RDiscount:
require 'bluecloth'
Tilt.register 'markdown', BlueClothTemplate
Tilt.register 'mkd', BlueClothTemplate
Tilt.register 'md', BlueClothTemplate
get '/' do
markdown :index
end
Renders ./views/index.md with BlueCloth.
The RedCloth gem/library is required to render Textile templates:
## You'll need to require redcloth in your app
require "redcloth"
get '/' do
textile :index
end
Renders ./views/index.textile.
It is not possible to call methods from textile, nor to pass locals to it. You therefore will usually use it in combination with another rendering engine:
erb :overview, :locals => { :text => textile(:introduction) }
Note that you may also call the textile method from within other templates:
%h1 Hello From Haml! %p= textile(:greetings)
The rdoc gem/library is required to render RDoc templates:
## You'll need to require rdoc in your app
require "rdoc"
get '/' do
rdoc :index
end
Renders ./views/index.rdoc.
It is not possible to call methods from rdoc, nor to pass locals to it. You therefore will usually use it in combination with another rendering engine:
erb :overview, :locals => { :text => rdoc(:introduction) }
Note that you may also call the rdoc method from within other templates:
%h1 Hello From Haml! %p= rdoc(:greetings)
The radius gem/library is required to render Radius templates:
## You'll need to require radius in your app
require 'radius'
get '/' do
radius :index
end
Renders ./views/index.radius.
Since you cannot call Ruby methods (except for yield) from a Radius template, you almost always want to pass locals to it:
radius :index, :locals => { :key => 'value' }
The markaby gem/library is required to render Markaby templates:
## You'll need to require markaby in your app
require 'markaby'
get '/' do
markaby :index
end
Renders ./views/index.mab.
The coffee-script gem/library and at least one of the following options to execute JavaScript:
See github.com/josh/ruby-coffee-script for an updated list of options.
Now you can render CoffeeScript templates:
## You'll need to require coffee-script in your app
require 'coffee-script'
get '/application.js' do
coffee :application
end
Renders ./views/application.coffee.
get '/' do
haml '%div.title Hello World'
end
Renders the embedded template string.
Templates are evaluated within the same context as route handlers. Instance variables set in route handlers are direcly accessible by templates:
get '/:id' do
@foo = Foo.find(params[:id])
haml '%h1= @foo.name'
end
Or, specify an explicit Hash of local variables:
get '/:id' do
foo = Foo.find(params[:id])
haml '%h1= foo.name', :locals => { :foo => foo }
end
This is typically used when rendering templates as partials from within other templates.
Templates may be defined at the end of the source file:
require 'sinatra'
get '/' do
haml :index
end
__END__
@@ layout
%html
= yield
@@ index
%div.title Hello world!!!!!
NOTE: Inline templates defined in the source file that requires sinatra are automatically loaded. Call enable :inline_templates explicitly if you have inline templates in other source files.
Templates may also be defined using the top-level template method:
template :layout do
"%html\n =yield\n"
end
template :index do
'%div.title Hello World!'
end
get '/' do
haml :index
end
If a template named "layout" exists, it will be used each time a template is rendered. You can individually disable layouts by passing :layout => false or disable them by default via set :haml, :layout => false.
get '/' do
haml :index, :layout => !request.xhr?
end
To associate a file extension with a template engine, use Tilt.register. For instance, if you like to use the file extension tt for Textile templates, you can do the following:
Tilt.register :tt, Tilt[:textile]
First, register your engine with Tilt, then create a rendering method:
Tilt.register :myat, MyAwesomeTemplateEngine
helpers do
def myat(*args) render(:myat, *args) end
end
get '/' do
myat :index
end
Renders ./views/index.myat. See github.com/rtomayko/tilt to learn more about Tilt.
Use the top-level helpers method to define helper methods for use in route handlers and templates:
helpers do
def bar(name)
"#{name}bar"
end
end
get '/:name' do
bar(params[:name])
end
Before filters are evaluated before each request within the same context as the routes will be and can modify the request and response. Instance variables set in filters are accessible by routes and templates:
before do
@note = 'Hi!'
request.path_info = '/foo/bar/baz'
end
get '/foo/*' do
@note #=> 'Hi!'
params[:splat] #=> 'bar/baz'
end
After filter are evaluated after each request within the same context and can also modify the request and response. Instance variables set in before filters and routes are accessible by after filters:
after do
puts response.status
end
Note: Unless you use the `body` method rather than just returning a String from the routes, the body will not yet be available in the after filter, since it is generated later on.
Filters optionally taking a pattern, causing them to be evaluated only if the request path matches that pattern:
before '/protected/*' do
authenticate!
end
after '/create/:slug' do |slug|
session[:last_slug] = slug
end
To immediately stop a request within a filter or route use:
halt
You can also specify the status when halting:
halt 410
Or the body:
halt 'this will be the body'
Or both:
halt 401, 'go away!'
With headers:
halt 402, {'Content-Type' => 'text/plain'}, 'revenge'
A route can punt processing to the next matching route using pass:
get '/guess/:who' do
pass unless params[:who] == 'Frank'
'You got me!'
end
get '/guess/*' do
'You missed!'
end
The route block is immediately exited and control continues with the next matching route. If no matching route is found, a 404 is returned.
The incoming request object can be accessed from request level (filter, routes, error handlers) through the `request` method:
# app running on http://example.com/example
get '/foo' do
request.body # request body sent by the client (see below)
request.scheme # "http"
request.script_name # "/example"
request.path_info # "/foo"
request.port # 80
request.request_method # "GET"
request.query_string # ""
request.content_length # length of request.body
request.media_type # media type of request.body
request.host # "example.com"
request.get? # true (similar methods for other verbs)
request.form_data? # false
request["SOME_HEADER"] # value of SOME_HEADER header
request.referer # the referer of the client or '/'
request.user_agent # user agent (used by :agent condition)
request.cookies # hash of browser cookies
request.xhr? # is this an ajax request?
request.url # "http://example.com/example/foo"
request.path # "/example/foo"
request.ip # client IP address
request.secure? # false
request.env # raw env hash handed in by Rack
end
Some options, like script_name or path_info can also be written:
before { request.path_info = "/" }
get "/" do
"all requests end up here"
end
The request.body is an IO or StringIO object:
post "/api" do
request.body.rewind # in case someone already read it
data = JSON.parse request.body.read
"Hello #{data['name']}!"
end
Run once, at startup, in any environment:
configure do
# setting one option
set :option, 'value'
# setting multiple options
set :a => 1, :b => 2
# same as `set :option, true`
enable :option
# same as `set :option, false`
disable :option
# you can also have dynamic settings with blocks
set(:css_dir) { File.join(views, 'css') }
end
Run only when the environment (RACK_ENV environment variable) is set to :production:
configure :production do
...
end
Run when the environment is set to either :production or :test:
configure :production, :test do
...
end
You can access those options via settings:
configure do
set :foo, 'bar'
end
get '/' do
settings.foo? # => true
settings.foo # => 'bar'
...
end
Error handlers run within the same context as routes and before filters, which means you get all the goodies it has to offer, like haml, erb, halt, etc.
When a Sinatra::NotFound exception is raised, or the response‘s status code is 404, the not_found handler is invoked:
not_found do
'This is nowhere to be found.'
end
The error handler is invoked any time an exception is raised from a route block or a filter. The exception object can be obtained from the sinatra.error Rack variable:
error do
'Sorry there was a nasty error - ' + env['sinatra.error'].name
end
Custom errors:
error MyCustomError do
'So what happened was...' + request.env['sinatra.error'].message
end
Then, if this happens:
get '/' do
raise MyCustomError, 'something bad'
end
You get this:
So what happened was... something bad
Alternatively, you can install error handler for a status code:
error 403 do
'Access forbidden'
end
get '/secret' do
403
end
Or a range:
error 400..510 do
'Boom'
end
Sinatra installs special not_found and error handlers when running under the development environment.
When using send_file or static files you may have mime types Sinatra doesn‘t understand. Use mime_type to register them by file extension:
mime_type :foo, 'text/foo'
You can also use it with the content_type helper:
content_type :foo
Sinatra rides on Rack, a minimal standard interface for Ruby web frameworks. One of Rack‘s most interesting capabilities for application developers is support for "middleware" — components that sit between the server and your application monitoring and/or manipulating the HTTP request/response to provide various types of common functionality.
Sinatra makes building Rack middleware pipelines a cinch via a top-level use method:
require 'sinatra'
require 'my_custom_middleware'
use Rack::Lint
use MyCustomMiddleware
get '/hello' do
'Hello World'
end
The semantics of use are identical to those defined for the Rack::Builder DSL (most frequently used from rackup files). For example, the use method accepts multiple/variable args as well as blocks:
use Rack::Auth::Basic do |username, password|
username == 'admin' && password == 'secret'
end
Rack is distributed with a variety of standard middleware for logging, debugging, URL routing, authentication, and session handling. Sinatra uses many of of these components automatically based on configuration so you typically don‘t have to use them explicitly.
Sinatra tests can be written using any Rack-based testing library or framework. Rack::Test is recommended:
require 'my_sinatra_app'
require 'test/unit'
require 'rack/test'
class MyAppTest < Test::Unit::TestCase
include Rack::Test::Methods
def app
Sinatra::Application
end
def test_my_default
get '/'
assert_equal 'Hello World!', last_response.body
end
def test_with_params
get '/meet', :name => 'Frank'
assert_equal 'Hello Frank!', last_response.body
end
def test_with_rack_env
get '/', {}, 'HTTP_USER_AGENT' => 'Songbird'
assert_equal "You're using Songbird!", last_response.body
end
end
NOTE: The built-in Sinatra::Test module and Sinatra::TestHarness class are deprecated as of the 0.9.2 release.
Defining your app at the top-level works well for micro-apps but has considerable drawbacks when building reusable components such as Rack middleware, Rails metal, simple libraries with a server component, or even Sinatra extensions. The top-level DSL pollutes the Object namespace and assumes a micro-app style configuration (e.g., a single application file, ./public and ./views directories, logging, exception detail page, etc.). That‘s where Sinatra::Base comes into play:
require 'sinatra/base'
class MyApp < Sinatra::Base
set :sessions, true
set :foo, 'bar'
get '/' do
'Hello world!'
end
end
The methods available to Sinatra::Base subclasses are exactly as those available via the top-level DSL. Most top-level apps can be converted to Sinatra::Base components with two modifications:
Sinatra::Base is a blank slate. Most options are disabled by default, including the built-in server. See Options and Configuration for details on available options and their behavior.
Contrary to common believes, there is nothing wrong with classic style. If it suits your application, you do not have to switch to a modular application.
There are only two downsides compared to modulare style:
There is no reason you cannot mix modular and classic style.
If switching from one style to the other, you should be aware of slight differences in the setting:
Setting Classic Modular app_file file loading sinatra nil run $0 == app_file false logging true false method_override true false inline_templates true false
There are two common options for starting a modular app, activly starting with run!:
# my_app.rb
require 'sinatra/base'
class MyApp < Sinatra::Base
# ... app code here ...
# start the server if ruby file executed directly
run! if app_file == $0
end
Start with:
ruby my_app.rb
Or with a config.ru, which allows using any Rack handler:
# config.ru require 'my_app' run MyApp
Run:
rackup -p 4567
Write your app file:
# app.rb
require 'sinatra'
get '/' do
'Hello world!'
end
And a corresponding config.ru:
require 'app' run Sinatra::Application
Good signs you probably want to use a config.ru:
There is no need to switch to a config.ru only because you switched to modular style, and you don‘t have to use modular style for running with a config.ru.
Not only is Sinatra able to use other Rack middleware, any Sinatra application can in turn be added in front of any Rack endpoint as middleware itself. This endpoint could be another Sinatra application, or any other Rack-based application (Rails/Ramaze/Camping/…).
require 'sinatra/base'
class LoginScreen < Sinatra::Base
enable :sessions
get('/login') { haml :login }
post('/login') do
if params[:name] = 'admin' and params[:password] = 'admin'
session['user_name'] = params[:name]
else
redirect '/login'
end
end
end
class MyApp < Sinatra::Base
# middleware will run before filters
use LoginScreen
before do
unless session['user_name']
halt "Access denied, please <a href='/login'>login</a>."
end
end
get('/') { "Hello #{session['user_name']}." }
end
The scope you are currently in determines what methods and variables are available.
Every Sinatra application corresponds to a subclass of Sinatra::Base. If you are using the top level DSL (require ‘sinatra‘), then this class is Sinatra::Application, otherwise it is the subclass you created explicitly. At class level you have methods like `get` or `before`, but you cannot access the `request` object or the `session`, as there only is a single application class for all requests.
Options created via `set` are methods at class level:
class MyApp < Sinatra::Base
# Hey, I'm in the application scope!
set :foo, 42
foo # => 42
get '/foo' do
# Hey, I'm no longer in the application scope!
end
end
You have the application scope binding inside:
You can reach the scope object (the class) like this:
For every incoming request, a new instance of your application class is created and all handler blocks run in that scope. From within this scope you can access the `request` and `session` object or call rendering methods like `erb` or `haml`. You can access the application scope from within the request scope via the `settings` helper:
class MyApp < Sinatra::Base
# Hey, I'm in the application scope!
get '/define_route/:name' do
# Request scope for '/define_route/:name'
@value = 42
settings.get("/#{params[:name]}") do
# Request scope for "/#{params[:name]}"
@value # => nil (not the same request)
end
"Route defined!"
end
end
You have the request scope binding inside:
The delegation scope just forwards methods to the class scope. However, it does not behave 100% like the class scope, as you do not have the class’ binding: Only methods explicitly marked for delegation are available and you do not share variables/state with the class scope (read: you have a different `self`). You can explicitly add method delegations by calling Sinatra::Delegator.delegate :method_name.
You have the delegate scope binding inside:
Have a look at the code for yourself: here‘s the Sinatra::Delegator mixin being included into the main namespace.
Sinatra applications can be run directly:
ruby myapp.rb [-h] [-x] [-e ENVIRONMENT] [-p PORT] [-o HOST] [-s HANDLER]
Options are:
-h # help -p # set the port (default is 4567) -o # set the host (default is 0.0.0.0) -e # set the environment (default is development) -s # specify rack server/handler (default is thin) -x # turn on the mutex lock (default is off)
If you would like to use Sinatra‘s latest bleeding code, feel free to run your application against the master branch, it should be rather stable.
We also push out prerelease gems from time to time, so you can do a
gem install sinatra --pre
To get some of the latest features.
If you want to run your application with the latest Sinatra, using Bundler is the recommend way.
First, install bundler, if you haven‘t:
gem install bundler
Then, in you project directory, create a Gemfile:
source :rubygems gem 'sinatra', :git => "git://github.com/sinatra/sinatra.git" # other dependencies gem 'haml' # for instance, if you use haml gem 'activerecord', '~> 3.0' # maybe you also need ActiveRecord 3.x
Note that you will have to list all your applications dependencies in there. Sinatra‘s direct dependencies (Rack and Tilt) will however be automatically fetched and added by Bundler.
Now you can run your app like this:
bundle exec ruby myapp.rb
Create a local clone and run your app with the sinatra/lib directory on the LOAD_PATH:
cd myapp git clone git://github.com/sinatra/sinatra.git ruby -Isinatra/lib myapp.rb
To update the Sinatra sources in the future:
cd myapp/sinatra git pull
You can build the gem on your own:
git clone git://github.com/sinatra/sinatra.git cd sinatra rake sinatra.gemspec rake install
If you install gems as root, the last step should be
sudo rake install